R01UH0040EJ0100 Rev.1.00
Page 144 of 1657
Sep 8, 2011
RX630 Group
3. Operating Modes
3.3
Details of Operating Modes
3.3.1
Single-Chip Mode
In this mode, the on-chip ROM is enabled or disabled, the external bus is disabled (SYSCR0.EXBE bit = 0), and all I/O
ports can be used as input/output ports.
The on-chip ROM is enabled when this LSI is started. While the on-chip ROM is enabled (SYSCR0.ROME bit = 1), it
can be disabled by clearing the SYSCR0.ROME bit to 0. While the on-chip ROM is disabled (SYSCR0.ROME bit = 0),
it cannot be enabled by setting the SYSCR0.ROME bit to 1.
Setting the SYSCR0.EXBE bit to 1 causes a transition to on-chip ROM enabled extended mode or on-chip ROM
disabled extended mode where the external bus is available.
3.3.2
On-Chip ROM Enabled Extended Mode
In this mode, the on-chip ROM is enabled (SYSCR0.ROME bit = 1) and the external bus is available as external
extended mode (SYSCR0.EXBE bit = 1). This mode allows some I/O ports to be used as data bus input/output, address
The external bus width can be changed by the setting of external bus width selection (CSnCR.BSIZE[1:0] bits
Writing 0 to the SYSCR0.EXBE bit causes a transition to single-chip mode (on-chip ROM enabled).
Writing 0 to the SYSCR0.ROME bit causes a transition to on-chip ROM disabled extended mode.
3.3.3
On-Chip ROM Disabled Extended Mode
In this mode, the on-chip ROM is disabled (SYSCR0.ROME bit = 0) and the external bus is available as external
extended mode (SYSCR0.EXBE bit = 1). This mode allows some I/O ports to be used as data bus input/output, address
The external bus width can be changed by the setting of external bus width selection (CSnCR.BSIZE[1:0] bits
In this mode, the on-chip ROM cannot be enabled by setting the SYSCR0.ROME bit to 1.
Writing 0 to the SYSCR0.EXBE bit causes a transition to single-chip mode (on-chip ROM disabled).
3.3.4
Boot Mode (SCI boot)
Boot mode (SCI boot) is provided for the ROM. This mode functions in the same manner as single-chip mode except for
3.3.5
User Boot Mode
User boot mode is provided for executing the user boot mode. This mode functions in the same manner as single-chip
Transition to software standby mode or deep software standby must not be made in user boot mode.
3.3.6
USB Boot Mode
USB boot mode is provided for the ROM. This mode functions in the same manner as single-chip mode except for data